Endoscopic mucosal resection of flat and depressed types of early colorectal cancer

Endoscopic treatment of large superficial colorectal tumors: a case series of 200 endoscopic submucosal dissections (with video)

BACKGROUND

Endoscopic submucosal dissection (ESD) is accepted as a minimally invasive treatment for early gastric cancer; however, it is not widely used in the colorectum because of its technical difficulty.

OBJECTIVE

To determine the feasibility of using ESD for treating large superficial colorectal tumors and to evaluate the clinical outcome.

DESIGN AND SETTING

Case series conducted at the National Cancer Center Hospital in Tokyo.

PATIENTS

A total of 198 consecutive patients were treated for 200 lesions.

INTERVENTIONS

Procedures were performed, before July 2004, by using a monopolar needle knife or an insulation-tipped knife (IT knife). After July 2004, the procedures were performed by using a bipolar needle knife or an IT knife. After injection of glycerol and sodium hyaluronate acid into the submucosal (sm) layer, a circumferential incision was made and sm dissection was performed endoscopically.

MAIN OUTCOME MEASUREMENTS

The en bloc resection rate was 84% and the curative resection rate was 83%.

RESULTS

Among the 200 ESDs, 51 involved tubular adenomas, 99 intramucosal cancers, 22 minute sm cancers, and 28 sm deep cancers. The median operation time was 90 minutes, and the mean size of resected specimens was 38 mm (range, 20-150 mm). Perforations occurred in 10 cases (5%) and postoperative bleeding in 4 cases (2%), but only 1 perforation case needed emergency surgery, because endoscopic clipping was ineffective.

LIMITATIONS

No long-term outcome data yet.

CONCLUSIONS

ESD is a feasible technique for treating large superficial colorectal tumors, because it provides a higher en bloc resection rate and is less invasive than surgical resection.

Thin endoscope-assisted endoscopic submucosal dissection for large colorectal tumors (with videos)

BACKGROUND

Endoscopic submucosal dissection (ESD) enables direct submucosal dissection so even large early stage GI tumors can be resected en bloc. Colorectal ESD is technically more difficult, however, and there is an increased risk of complications such as perforation and bleeding compared with gastric ESD. As a result, further refinements are required in this procedure.

OBJECTIVE

Our purpose was to evaluate thin endoscope-assisted (TEA) ESD, a new traction system for improving submucosal cutting line visualization.

DESIGN

Case series.

SETTING

Okayama University Hospital.

MAIN OUTCOME MEASUREMENTS

Efficacy and safety of the TEA-ESD procedure.

RESULTS

Three cases of large, flat, elevated colorectal tumors (laterally spreading tumors) in the rectum and rectosigmoid colon were safely and successfully removed en bloc without complications. Total procedure times were 3 hours, 40 minutes, and 30 minutes with resected specimens measuring 70 x 68 mm, 38 x 35 mm, and 30 x 20 mm, respectively.

LIMITATIONS

TEA-ESD was performed in only the rectum and rectosigmoid colon.

CONCLUSIONS

This limited case series demonstrated that large laterally spreading tumors in the rectum and rectosigmoid colon could be safely resected en bloc with TEA-ESD.

Small, flat colorectal cancers in the UK population: an analysis of resected specimens

OBJECTIVES

To establish the prevalence of small, flat carcinomas in surgically resected colon. To determine whether tumour morphology influences stage at presentation.

METHOD

1763 surgically resected colorectal cancers from one UK centre excised between 1995 and 2004 were examined. Age 69 years, (42-90), M:F equal. Sixty-one tumours < or =20 mm across were identified. Slides were reviewed by a consultant histopathologist and classified using Japanese Research Society Classification, JRSC and TNM staging. Fisher's exact test was used for analysis.

RESULTS

In 61 small cancers, 64% (39/61) showed flat morphology and 33% (20/61) polypoid. Two lesions were unclassifiable. Prevalence was 2.2% of all resected colorectal cancers. More T1 tumours at presentation were polypoid, (30% vs. 8%; P = 0.033). T3 tumours were more likely to be flat than polypoid, (49% vs. 20%; P = 0.016). Infiltration into musclaris mucosa occurred in 77% (30/39) flat tumours. Rates of metastases were high in both groups, (30% polypoid vs. 39% flat, not significant).

CONCLUSIONS

The prevalence of small, flat cancers in resected specimens in the UK concurs with that of Japanese studies. Small, flat cancers should be staged carefully because of high rates of T3/4 disease. The results support the theory of accelerated carcinogenesis in flat cancers.

Immunohistochemical molecular markers as predictors of curability of endoscopically resected submucosal colorectal cancer

AIM: To clarify the usefulness of immunohistochemical molecular markers in predicting lymph node metastasis of submucosal colorectal cancer.

METHODS: We examined microvessel density, lymphatic vessel density, the Ki-67 labeling index, expression of MUC1 and Matrix metalloproteinase-7 (MMP-7) in tumor cells, and expression of cathepsin D in stromal cells at the invasive front by immunostaining of samples resected from 214 patients with submucosal colorectal cancer. Pathologic features were assessed on hematoxylin-eosin-stained samples. We evaluated the relations between clinicopathologic/immunohistochemical features and lymph node metastasis.

RESULTS: Lesions of the superficial type, with an unfavorable histologic grade, budding, lymphatic involvement, high microvessel density (≥ 40), high lymphatic vessel density (≥ 9), high Ki-67 labeling index (≥ 42), and positivity of MUC1, cathepsin D, and MMP-7 showed a significantly high incidence of lymph node metastasis. Multivariate analysis revealed that high microvessel density, unfavorable histologic grade, cathepsin D positivity, high lymphatic vessel density, superficial type, budding, and MUC1 positivity were independent risk factors for lymph node metastasis. A combined examination with four independent immunohistochemical markers (microvessel density, cathepsin D, lymphatic vessel density, and MUC1) revealed that all lesions that were negative for all markers or positive for only one marker were negative for lymph node metastasis.

CONCLUSION: Analysis of a combination of immuno-histochemical molecular markers in endoscopically resected specimens of submucosal colorectal cancer allows prediction of curability regardless of the pathologic features visible of hematoxylin-eosin-stained sections.

Magnification chromo-colonoscopy

Chromoscopic colonoscopy using indigo carmine is indispensable for the accurate detection of flat neoplastic lesions. In particular, the dye spray technique facilitates the detection of both flat hyperplastic polyps and highly dysplastic lesions. However, magnification chromo-colonoscopy discriminates adenomas from hyperplastic polyps with greater accuracy than conventional methods by showing distinct and visible pit patterns. A pit pattern represents crypt orifices, which reflect the underlying histological structures and colonoscopists can make histological predictions by observing the pit patterns without obtaining biopsy specimens. The pit patterns are classified as types I, II, IIIL, IIIs, IV and V based on histological characterization of normal mucosa, hyperplastic polyp, polypoid adenoma, flat adenoma, tubulo-villous adenoma and cancerous tissue, respectively. In previous reports, overall accuracy ranged from 80 to 95%. In addition, magnification chromo-colonoscopy is useful for the diagnosis of early cancer associated with substantial invasion of the submucosa, in which type V pits are subclassified as types V-I and V-N. The presence of type V-N pits is significant in correlation to cancer with substantial invasion of the submucosa. Magnification chromo-colonoscopy is useful in clinical decision-making when deciding whether endoscopic resection or bowel resection is the appropriate initial procedure to treat lesions.

State of the art on endoscopic mucosal resection and endoscopic submucosal dissection

Endoscopic mucosal resection (EMR) and endoscopic submucosal dissection (ESD) provide new alternatives for minimally invasive treatment of superficial gastrointestinal malignancies. Evidence suggests that these techniques can be performed safely and have comparable outcomes to surgery with less morbidity and better quality of life due to their tissue-sparing nature when compared with conventional surgery. Although the techniques and accessories have become standardized, there is room for improvement, and further research and development are required. Current challenges facing American gastroenterologists or endoscopic surgeons include access to training and lack of appropriate reimbursement for these heavy-weighted and technically demanding procedures. Nevertheless, EMR and ESD are here to stay and are only the first steps toward true radical endoluminal resection of GI malignancies.

Endoscopic submucosal dissection for colorectal neoplasia: possibility of standardization

BACKGROUND

Endoscopic submucosal dissection (ESD) has been positively applied to and gradually standardized for early stomach cancer, particularly in Japan. However, because it is technically difficult to perform ESD of the colon, ESD is not a commonly used technique.

OBJECTIVE

The aim of this study was to evaluate the possibility of standardizing colorectal ESD.

SETTING

ESD was performed at the Department of Endoscopy, Hiroshima University Hospital.

DESIGN

Time required for ESD, rate of complete en bloc resection, complication, and postoperative local persistence and recurrence were investigated retrospectively in 70 cases of colorectal neoplasia, wherein the lesion was more than 20 mm in diameter.

INTERVENTIONS

All lesions were resected by ESD.

RESULTS

The average (+/-SD) time required for ESD was 70.5+/-45.9 minutes (range, 15-180 minutes), and the histologic rate of complete en bloc resection was 80.0% (56/70). With regard to complication, 1.4% of cases of postoperative hemorrhage (1/70) and 10.0% of cases of perforation (7/70) were observed in total. The rate of perforation was investigated with respect to the type of knife used for ESD and the period after the induction of ESD. The rate of perforation markedly decreased with the practice of the technique. Moreover, the rate of perforation was high when an insulated-tip diathermic knife was used; practicing this technique was insufficient to reduce the rate of perforation. The average duration of follow-up was 614+/-289.5 days, and no case of local persistence and recurrence or metastasis was observed.

LIMITATIONS

The ESD technique depends on the level of each skill of each colonoscopist.

CONCLUSIONS

With regard to ESD of the colon, complication, eg, perforation, could be decreased by sufficient practice and selection of an appropriate knife. It is suggested that, in the near future, ESD will be standardized for the colon.

Effectiveness of sodium alginate as a submucosal injection material for endoscopic mucosal resection in animal

BACKGROUND/AIMS

Although various solutions are being tested for submucosal injection during endoscopic resection, ideal solution has not been established yet. We performed an animal study to evaluate the possibility of sodium alginate as an ideal submucosal injection solution for endoscopic mucosal resection (EMR).

METHODS

To compare the lesion-lifting properties of different solutions, injection was done to the submucosal layer of porcine stomach. Then the height of mucosal elevation was measured. In addition, EMR was performed after submucosal injection of sodium alginate solution in six dogs. Two were euthanized after 30 minutes of endoscopic observation while the others were euthanized after 1-4 weeks. Retrieved stomachs were examined microscopically.

RESULTS

Sodium alginate and sodium hyaluronate solutions maintained longer elevation of the submucosal layer than other solutions. There was no significant difference in the height between two solutions. A clear separation of the mucosal layer from the proper muscle layer was achieved by injecting sodium alginate solution. Histological examination of EMR-induced artificial ulcers revealed no apparent tissue damage and showed normal healing process.

CONCLUSIONS

Sodium alginate solution creates a sufficient submucosal fluid cushion without apparent tissue damage. It can be considered as an effective submucosal injection material.

Minute depressed-type submucosal invasive cancer-5 mm in diameter with intermediate lymph-node metastasis: report of a case

We report a rare case of colon cancer in which a depressed-type tumor only 5 mm in diameter invaded the submucosal layer and produced intermediate lymph node metastasis. A 47-year-old male received a total colonoscopy for a depressed-type lesion with marginal elevation in the sigmoid colon. The lesion measured 5 mm in diameter. On chromoendoscopic examination, the depression was clearly demarcated and an irregular pit pattern was identified in the demarcated area by magnification suggesting invasion of the submucosal layer requiring surgery. Laparoscopic-assisted sigmoidectomy was performed and the resected specimen demonstrated well-differentiated adenocarcinoma. The depth of invasion was only 900 microm. There was no lymphovascular invasion although not only paracolic, but also intermediate lymph node metastasis was detected. There have been some reports about small depressed-type colorectal cancer invading the submucosal layer; however, intermediate LN metastasis is very rare in submucosal colorectal cancer. In this case, there were two noteworthy points: 1) despite the small size, submucosal invasion could be estimated preoperatively, therefore, a successful lymph node dissection was performed by laparoscopic surgery; and 2) although this depressed-type cancer invaded the submucosal layer only 900 microm and there was no lymphovascular invasion, intermediate lymph node metastasis was detected.

Operative colonoscopy in cancer patients

Gastrointestinal endoscopy has experienced tremendous developments in technology and equipment over the past decades. It is not only a diagnostic tool, but it also allows some interventional treatments in benign and malignant digestive diseases. Operative colonoscopy has been used to perform curative treatment of various kinds of polyps, flat and carpet-like adenomas and early colorectal carcinomas. Endoscopic palliative treatment strategies, such as the placement of self-expandable metal stents (SEMS), laser ablation, photodynamic therapy (PDT), argon plasma coagulation (APC), electrocoagulation, and injection therapy, have been proved to effectively alleviate advanced colorectal cancer (CRC) associated symptoms and maintain or improve the quality of the patient's remaining life.

Clinicopathologic and immunohistochemical study of small apparently "de novo" colorectal adenocarcinomas

Rarely, adenocarcinomas of the colorectum develop as small (< or =1.0 cm) rapidly invasive tumors without an obvious adenomatous or "in situ" component. These tumors have been termed "de novo" carcinomas. Although it is believed by some that these tumors are more aggressive than conventional large adenocarcinomas with an identifiable in situ component, little is known about the biologic characteristics and natural history of these lesions. The aim of this study was to evaluate and compare the pathologic features, biologic characteristics, and natural history of small apparently de novo invasive colorectal adenocarcinomas with conventional large (>1.0 cm) carcinomas. Routinely processed specimens from 20 patients (M/F ratio: 13/7; mean age: 65 y) with small apparently de novo invasive colorectal adenocarcinomas (all < or =1.0 cm in size) were evaluated for a variety of clinical and pathologic features. In addition, immunostains for p53, beta-catenin, DPC4, hMLH1, hMSH2, and MGMT were evaluated in all cases. The findings in this group of cases were compared with those from 20 control patients (M/F ratio: 8/12; mean age: 60 y) with stage-matched conventional "large" colorectal adenocarcinomas (all >1.0 cm in size). Patients were followed for a mean of 52.6 and 60.6 months, respectively, for the 2 groups. Small apparently de novo invasive adenocarcinomas were present in the left colon, transverse colon, and right colon in 85%, 10%, and 5% of cases, respectively. Their mean size was 7 mm (range: 3 to 10 mm). All cases were stage T1 and the majority were moderately differentiated (75%). Only 1 (5%) patient had lymph node metastases. Two (10%) cases were mucinous and only 1 (5%) showed prominent tumor infiltrating lymphocytes. Upon complete sectioning of the tissue blocks of tumor, residual foci of adenomatous epithelium were present in 16/20 (80%) cases, of which 75% contained foci of high-grade dysplasia. P53 and nuclear beta-catenin staining was present in 70% and 85% of cases, respectively, but only 5 cases (25%) showed loss of DPC4. Loss of MGMT expression was seen in 5 cases (25%), loss of hMSH2 in only 1 case (5%), and none showed loss of hMLH1. Only 2 patients (10%) developed visceral metastases upon follow-up. Control patients had similar demographic features, clinical outcome, anatomic distribution of tumors, degree of differentiation, and prevalence of positivity for the immunostains noted above, to the study cases. In our patient population, true small de novo colorectal adenocarcinomas, tumors that lack an identifiable adenomatous component, are exceedingly rare, because complete tissue sectioning reveals residual adenomatous tissue in the majority of cases. The biologic characteristics and natural history of small carcinomas with a minimal dysplastic component, and those with no identifiable adenomatous component, are similar to conventional large (>1 cm) adenocarcinomas, and, thus, they should probably be treated similarly.

Novel colorectal endoscopic in vivo imaging and resection practice: a short practice guide for interventional endoscopists

Colorectal cancer remains a leading cause of cancer death in the UK. With the advent of screening programmes and developing techniques designed to treat and stage colorectal neoplasia, there is increasing pressure on the colonoscopist to keep up to date with the latest practices in this area. This review looks at the basic principles behind endoscopic mucosal resection and forward to the potential endoscopic tools, including high-magnification chromoscopic colonoscopy, high-frequency miniprobe ultrasound and confocal laser scanning endomicroscopic colonoscopy, that may soon become part of routine colorectal cancer management.

The advantages of volume rendering in three-dimensional endosonography of the anorectum

Anorectal diseases require imaging for proper case management. At present, endoanal ultrasonography and endorectal ultrasonography have become important parts of diagnostic workup of patients with fecal incontinence, perianal fistulas, and rectal cancer and provides sufficient information for clinical decision-making in many cases. However, with the currently available ultrasonographic equipment and techniques, a good deal of relevant information may remain hidden. The advent of high-resolution three-dimensional endoluminal ultrasound, constructed from a synthesis of standard two-dimensional cross-sectional images, and of "Volume Render Mode," a technique to analyze information inside a three-dimensional volume by digitally enhancing individual voxels, promises to revolutionize diagnosis of pelvic floor disorders. By use of the different postprocessing display parameters, the volume-rendered image provides better visualization performance when there are not large differences in the signal levels of pathologic structures compared with surrounding tissues. The anatomic structures in the pelvis, the axial and longitudinal extension of anal sphincter defects, the anatomy of the fistulous tract in complex perianal sepsis, and the presence of slight or massive submucosal invasion in early rectal cancer may be imaged in greater detail. This additional information will bring an improvement for both planning and conduct of surgical procedures.

Depressed-type of early colon cancer with extensive lymph node metastasis

Early colorectal cancer (ECC) is defined as invasive tumor limited to the colonic and rectal mucosa or submucosa, regardless of the presence or absence of lymph node metastasis. The incidence of lymph node metastasis in ECC ranges from 0 to 15.4%, and risk factors include depth of submucosal invasion, growth patterns (polypoid or non-polypoid), histologic subclassification, and lymphatic invasion. Of non-polypoid growth patterns, the depressed types of colorectal cancer have higher malignant potential than polypoid types, even for small sizes. Unfortunately, this type is also difficult to detect on colonoscopic examination. In this report, we describe a case of depressed type ECC with extensive lymph node metastasis without regional lymph node involvement.

Olympus Lucera high-resolution vascular ectasia mapping in combination with the type V crypt pattern for the invasive depth estimation and nodal disease estimation in Paris type II colorectal cancers: a comparative prospective analysis to 20 MHz ultrasound

INTRODUCTION

Flat and depressed neoplastic lesions of the colorectum [Paris type (PT) 0-II] localized to the superficial submucosal (sm) layer can be managed using endoscopic mucosal resection. Successful endoluminal management can be enhanced using endoscopic or ultrasound tools that help predict the degree of sm invasion. Previous studies addressing invasive depth estimation using high-magnification chromoscopic colonoscopy showed a low specificity for deep sm layer 3 invasion with miniprobe ultrasound demonstrating better nodal and T stage in vivo prediction. High-resolution vascular mapping of lesions can show microvascular superficial changes that may predict sm invasive disease.

AIMS

Vascular mapping in combination with high-magnification chromoscopic colonoscopy (HMCC) may provide an accurate tool for the invasive depth estimation of PT type II neoplastic lesions as compared with high frequency 20/12.5 MHz miniprobe ultrasound.

METHODS

Sixty-eight patients with a known diagnosis of PT II neoplasia were imaged using 3 "back to back" imaging modalities. Phase 1-vascular ectasia mapping; phase 2-HMCC with crypt analysis according to Nagata criteria; phase 3-12.5/20 MHz miniprobe ultrasound. Lesions predicted as T0/1/N0 were resected using endoscopic mucosal resection with the remaining referred for surgery. Each imaging modality was then compared with the resected histopathologic specimen used as the "gold standard."

RESULTS

N=68 lesions (19 sm1/13 sm2/36 sm3). Overall accuracy of Nagata criteria, Nagata criteria combined with vascular mapping, and ultrasound staging was 65%, 78%, and 94%, respectively (P<0.001) when observing the between phase differences. Fifty-two lesions were resected surgically. The prevalence of node positive disease was 16% (8/52) with the remaining 44/52 (84%) being confirmed pN0 at histopathology. The kappa coefficient of agreement between invasive depth estimation (using histopathology as the gold standard), Nagata stage, Nagata stage plus vascular ectasia mapping and ultrasound stage was 0.47, 0.65, and 0.9, respectively. A significant improvement in between phase differences was observed (P=0.001).

CONCLUSIONS

This is the first study to address the in vivo clinical utility of vascular mapping in combination with HMCC for the T and N staging of PT II neoplasia. Combination imaging may provide an adequate clinical tool for both T and N stage assessment in vivo and help stratify those patients at high risk for T2/N1 disease that may benefit from further high-frequency miniprobe ultrasound (HFUS) assessment and possible primary surgical excision. This is important in the clinical context, given the high overall costs of a second HFUS examination, limitation of HFUS resources, and safe selection of patients undergoing primary endoscopic resection versus surgical resection.

Flat elevated lesions of the colon and rectum: a spectrum of neoplastic and nonneoplastic entities

The aim of this prospective study is to establish the frequency and the type (neoplastic and nonneoplastic) lesions defined endoscopically as flat elevated lesion (FEL) in the colon and rectum, as well as to compare flat adenomas (FAs) to polypoid lesions of the same size with morphometric and immunohistochemical analysis. One hundred nineteen patients were studied through fibrocolonoscopy with chromoscopy (indigo carmine spray). All detected lesions (total of 195) were removed, and FELs measuring 10 mm or smaller were also selected. Using histopathologic criteria, they were divided in neoplastic (adenomas and carcinomas) and nonneoplastic ones. In neoplastic lesions, the following parameters were evaluated to compare FAs with polypoid lesions: morphometric studies with Index of Structural Atypia (ISA) and Stratification Index (SI), evaluation of cellular proliferation with label index of Ki-67, and expression of p53 protein. Of 195 lesions resected, only 33 (17%) met the endoscopic requirements for FELs. Twelve (36.4%) were neoplastic and 21 (63.6%) considered nonneoplastic. Among the FAs, there were a percentage of high-grade (severe dysplasia) significantly more frequent than observed in polypoid lesions (16.7% vs 2.6%). In addition, the SI, Ki-67 label index and p53 positivity were significantly higher in FAs. The ISA also reached significant differences between both groups of adenomas. Non-neoplastic FELs included different entities such as hyperplasic polyps, focuses of colitis, normal mucosa, and scars. The endoscopic elements analyzed were shared between nonneoplastic FELs and FAs. A central depression, when air was properly insufflated, considered typical in neoplastic lesions, was frequently observed in nonneoplastic lesions. Following the endoscopic criteria of FELs, nonneoplastic lesions predominated over the adenomatous lesions, demonstrating that FELs and FAs are not homologous terms. The frequency of high-grade dysplasia was significantly more elevated in the adenomatous FELs than in polypoid adenomas. The ISA, SI, p53 expression, and Ki-67 label index were helpful in differentiating adenomatous FELs from polypoid lesions. Flat elevated lesions selected by endoscopic criteria are, in fact, a heterogeneous population of lesions.

Recent advances in chromoscopic colonoscopy and endomicroscopy

The basic rationale for secondary prevention of colorectal carcinoma is by endoscopic polypectomy. New technologies in the form of high-magnification or "zoom" colonoscopy complemented by chromoscopic agents permit early detection of neoplastic colorectal lesions, particularly flat and depressed types. Detailed morphologic characteristics of the surface crypt or "pit pattern" can be obtained with these techniques, enabling an in vivo "optical biopsy" and staging tool. Establishing suitability for endoscopic resection or surgical excision can be enhanced using these techniques. Furthermore, chromoscopic colonoscopy may have a role in routine endoscopic colorectal cancer surveillance programs in patients at high risk for colorectal neoplasia, such as those with long-standing ulcerative colitis and familial colorectal cancer syndromes. This review summarizes recent data regarding the prevalence and histopathologic characteristics of flat and depressed colorectal lesions in Western cohorts and describes how their detection and management can be improved by chromoscopy and magnification technology. We outline these techniques from a clinical perspective and describe the basic principles of endoscopic mucosal resection.

Flat-type colorectal advanced adenomas (laterally spreading tumors) have different genetic and epigenetic alterations from protruded-type advanced adenomas

Morphologically, colorectal adenomas can be divided into two groups, protruded-type and flat-type. However, the accurate frequencies of genetic and epigenetic alterations in flat-type colorectal advanced adenomas (laterally spreading tumors) have remained largely unknown. In the current study, we investigated genetic and epigenetic alterations in 101 flat-type colorectal advanced adenomas and 68 protruded-type colorectal advanced adenomas by using direct DNA sequencing and quantitative real-time PCR (MethyLight), respectively. KRAS mutation was detected in a significantly higher percentage of flat-type adenomas (35%) than in protruded-type adenomas (13%). When the samples were limited to the tumors in the distal colon, the difference of KRAS mutation was still significant. KRAS mutation in G-to-A transitions at codons 12 and 13 was detected in a significantly higher percentage of flat-type adenomas (26%) than in protruded-type adenomas (9%). BRAF and beta-catenin mutations were detected in 3 and 8% of the 101 flat-type adenomas, respectively. No significant difference was found between frequencies of those mutations in flat-type adenomas and protruded-type adenomas. Methylations of MGMT, CDKN2A (p16) and MLH1 were detected in 28, 33 and 9% of the 101 flat-type adenomas, respectively. CDKN2A methylation was detected in a significantly lower percentage of flat-type adenomas than in protruded-type adenomas (63%). Methylation of at least one gene was detected in a significantly lower percentage of flat-type adenomas (54%) than in protruded-type adenomas (78%). In conclusion, KRAS mutation was frequently detected in flat-type advanced adenomas and the mutational patterns in most of them with KRAS mutations were a transition from G-to-A. Therefore, these genetic alterations seem to play an important role in the development of flat-type advanced adenomas, especially in the distal colon. Epigenetic alterations infrequently occurred in flat-type advanced adenomas, suggesting that they have different genetic and epigenetic alterations from those of protruded-type advanced adenomas.

Relationship between molecular markers and endoscopic findings in laterally spreading tumors

BACKGROUND AND AIM

Characteristic clinicopathological features of laterally spreading tumors (LSTs) have been reported by endoscopists; however, only a few studies have been conducted on the biological features. These studies were not fully associated with the endoscopic findings of LSTs. The aim of this study was to estimate the biological features of each type of endoscopic finding of LST using two molecular markers, matrix metalloproteinase-7 (MMP-7) and beta-catenin.

METHODS

Expression of the molecular markers and the endoscopic findings were compared in 22 LSTs and 14 subpedunculated polyps. MMP-7 and beta-catenin were immunostained. Three types of representative endoscopic findings of LST were defined as segments in LSTs. They were 15 granular segments, seven large nodular segments, and seven flat segments that corresponded to the area composed of aggregates of similar size granules, large nodules of diameter more than 10 mm, and a flat surface with no granule, respectively.

RESULTS

Expression of MMP-7 and coexpression of MMP-7 and beta-catenin were higher in large nodular segments than in granular segments (P < 0.0167). Among the three types of segments, flat segments showed the highest expression densities of beta-catenin accumulated in the nucleus. Large nodular segments and subpedunculated polyps showed similar expression patterns for the molecular markers.

CONCLUSIONS

This study provides new and important information on the relationship between the molecular markers and endoscopic findings of LSTs.

Diagnostic significance of gently sloping depression and irregular margin in superficial elevated colorectal tumors

INTRODUCTION

Recently, superficial elevated colorectal tumors have been increasingly diagnosed after improvements in endoscopic instruments and techniques. However, their biological characteristics remain obscure and it is difficult to predict malignant potential. The aim of this study is to clarify the characteristics of superficial elevated tumors in endoscopic examination for the evaluation of malignant potential.

MATERIALS AND METHODS

Sixty-three resected superficial elevated colorectal tumors more than 10 mm in diameter were analyzed with regard to their morphological characteristics and histological findings. The samples were classified according to the presence of a gently sloping depression and irregular margin at the edge. Their depth of vertical invasion and the degree of depression were examined.

RESULTS

The rate of carcinoma in 27 lesions with a gently sloping depression was significantly higher than in 36 lesions with an even surface. The rate of carcinoma in 46 lesions with irregular margin was significantly higher than in 17 lesions without irregular margin. A multivariate analysis revealed that the coexistence of both IM and GSD was significantly associated with submucosal invasion. Statistical associations of age, tumor location, gender, and pathological grade with submucosal invasion were not observed.

CONCLUSIONS

In superficial elevated colorectal tumors, a gently sloping depression and irregular margin at the edge when viewed endoscopically may be a predictor of malignant potential. These characteristics should be given priority when deciding on treatment.

Lymphatic vessel density at the site of deepest penetration as a predictor of lymph node metastasis in submucosal colorectal cancer

PURPOSE

Lymph node metastasis is an important factor that influences curability after endoscopic treatment of submucosal colorectal cancer. This study was designed to determine the usefulness of identification of lymphatic vessels by immunohistochemistry in predicting lymph node metastasis of submucosal colorectal cancer.

METHODS

Lymphatic involvement was assessed by hematoxylin and eosin staining and podoplanin immunostaining on samples resected from 268 patients with submucosal colorectal cancer. Lymphatic vessel density was estimated by two investigators by average count of three fields (x200) in the area of greatest number of podoplanin-positive capillaries at the site of deepest submucosal penetration. Relations with other clinicopathologic parameters also were investigated.

RESULTS

Lesions with high lymphatic vessel density (> or =9 vessels per field) showed a significantly greater incidence of lymph node metastasis than did those with low lymphatic vessel density (<9 vessels per field; 23.3 vs. 8.4 percent). By multivariate analysis, lymphatic vessel density was determined to be an independent risk factor for lymph node metastasis of submucosal colorectal cancer (P = 0.0044). Lymphatic vessel density also correlated with tumor budding and the degree of inflammation at the invasive front.

CONCLUSIONS

Identification of lymphatic vessels by podoplanin immunostaining provides objective and accurate evaluation of lymphatic involvement. Lymphatic vessel density at the site of deepest penetration is a useful predictor of lymph node metastasis of submucosal colorectal cancer.

Perceptive errors in CT colonography

Published results to date have indicated a good per patient sensitivity of computed tomographic colonography (CTC) for colorectal cancer and for polyps measuring 10 mm or more together with a very good specificity. Sensitivity and specificity for polyps in the range of 6-10 mm are moderate. These results, however, can be achieved only with meticulous attention to technique including adequate colonic distention, and acquisition of supine and prone thin-section computed tomographic (CT) images. Moreover, there is a significant learning curve involved in the interpretation of CTC studies, with performance statistics improving with operator experience. Radiologists must be comfortable in reporting directly from workstation monitors and have access to and be familiar with software for multiplanar and endoluminal reconstructions. In addition to maximize polyp detection and minimize false positive results, reporting radiologists must have a working knowledge of normal colorectal anatomy and pathology on CTC and be familiar with potential pitfalls in interpretation. Besides the description of several possible causes for perceptive errors, also a literature search of perceptive errors in CTC is included in this paper.

Comparative study of conventional colonoscopy, chromoendoscopy, and narrow-band imaging systems in differential diagnosis of neoplastic and nonneoplastic colonic polyps

AIM

To identify the feasibility of the narrow-band imaging (NBI) method compared with that of conventional colonoscopy and chromoendoscopy for distinguishing neoplastic and nonneoplastic colonic polyps.

METHOD

This study enrolled consecutive patients who underwent colonoscopy using a conventional colonoscope between January and February 2006 at Chang-Gung Memorial Hospital, Linkou Medical Center, Taiwan. These 78 patients had 110 colorectal polyps. During the procedure, conventional colonoscopy first detected lesions, and then the NBI system was used to examine the capillary networks. Thereafter indigo carmine (0.2%) was sprayed directly on the mucosa surface prior to evaluating the crypts using a conventional colonoscope. The pit patterns were characterized using the classification system proposed by Kudo. Finally, a polypectomy or biopsy was performed for histological diagnosis.

RESULTS

Of the 110 colorectal polyps, 65 were adenomas, 40 were hyperplastic polyps, and five were adenocarcinomas. The NBI system and pit patterns for all lesions were analyzed. For differential diagnosis of neoplastic (adenoma and adenocarcinoma) and nonneoplastic (hyperplastic) polyps, the sensitivity of the conventional colonoscope for detecting neoplastic polyps was 82.9%, specificity was 80.0% and diagnostic accuracy was 81.8%, significantly lower than those achieved with the NBI system (sensitivity 95.7%, specificity 87.5%, accuracy 92.7%) and chromoendoscopy (sensitivity 95.7%, specificity 87.5%, accuracy 92.7%). Therefore, no significant difference existed between the NBI system and chromoendoscopy during differential diagnosis of neoplastic and nonneoplastic polyps.

CONCLUSION

The NBI system identified morphological details that correlate well with polyp histology by chromoendoscopy.

Mutational analysis of beta-catenin and the RAS-RAF signalling pathway in early flat-type colorectal tumours

Morphologically, early colorectal tumours can be divided into two groups, protruded-type and flat-type. However, little is known about genetic mechanisms of the latter. We investigated mutations of beta-catenin, KRAS, BRAF, and PIK3CA in 310 early colorectal tumours. beta-catenin mutation was detected in 7.1% of 310 tumours. beta-catenin mutation was detected in a significantly higher percentage of flat-type tumours with depressed areas (4/17, 23.5%) than in other tumours (18/293, 6.1%; p=0.0246). KRAS, BRAF, and PIK3CA mutations were detected in 21.6%, 5.4%, and 1.0% of 310 tumours, respectively. Concomitant mutations of beta-catenin and KRAS or BRAF were detected in seven tumours. Mutation of at least one gene was detected in a significantly higher percentage of flat-type tumour tissues (75/193, 38.9%) than in protruded-type tumour tissues (25/117, 21.4%; p=0.0014), and it was correlated significantly with size (p=0.0001). In conclusion, beta-catenin mutation seemed to play an important role in flat-type tumours, especially in those with depressed areas. The genetic abnormalities could arise and accumulate in the early stage of colorectal tumourigenesis, and seem to contribute to the development of flat-type tumour.

The influence of histopathologic criteria on the long-term prognosis of locally excised pT1 rectal carcinomas: results of local excision (transanal endoscopic microsurgery) and immediate reoperation

PURPOSE

Local excision of early rectal cancer is a controversial issue, which is in part because of differences in the evaluation of histopathologic criteria. This prospective study was designed to determine prognostic factors for recurrences and the need for reoperation.

METHODS

In 105 of 118 patients with pT1 carcinomas and local excision, results of recurrence rates and ten-year cancer-free survival were studied separately according to different histologic criteria (R0, R1, Rx, R < or = 1 mm, high-/low-risk situation), tumor localization (anterior, posterior, lateral wall and third of rectum), size, and degree of resection (full-thickness/partial wall). Patients were grouped into local excision (n = 89) and local excision followed by reoperation (n = 21). Risk classification was performed by division into "low-risk" carcinomas after local R0-resection (Group A) and unfavorable histologic results after local resection (R1, Rx, R < or = 1 mm, high-risk situation; Group B).

RESULTS

Local recurrence rates after local R0-resection of low-risk carcinomas were 6 percent, whereas patients in Group B with local resection were 39 percent. The recurrence risk in those patients was significantly reduced to 6 percent by reoperation (P = 0.015). In addition, ten-year, cancer-free survival was 93 percent in Group B after reoperation compared with 89 percent in patients of Group A after local excision alone.

CONCLUSIONS

Local R0-resection in cases with low-risk pT1 carcinomas represents an oncologically adequate therapy, which results in similar survival rates compared with primary radical surgery of pT1N0M0 rectal carcinomas. High recurrence rates are observed in tumors with unfavorable histologic result (Group B) requiring further treatment. In these cases immediate reoperation reduces the recurrence rate to 6 percent.

Histopathological risk factors for lymph node metastasis in submucosal invasive colorectal carcinoma of pedunculated or semipedunculated type

AIMS

To evaluate the histopathological risk factors for lymph node metastasis in cases of pedunculated or semipedunculated submucosal invasive colorectal carcinoma (SICC).

METHODS

A total of 48 patients with non-sessile SICC who underwent systematic lymph node dissection were included. Tumour size, histological grade, angiolymphatic invasion, tumour budding, dedifferentiation, objective submucosal invasion depth from the identified muscularis mucosa, relative invasion depth of the submucosal layer, and depth of stalk invasion were investigated histopathologically.

RESULTS

Lymph node metastasis was observed in seven cases (14.6%). Univariate analysis showed angiolymphatic invasion and tumour budding to be significantly associated with lymph node metastasis. Multivariate analysis showed that tumour budding was the only independent factor associated with lymph node metastasis in cases of non-sessile SICC.

CONCLUSIONS

Results indicate that tumour budding is a useful risk factor for predicting lymph node metastasis in cases of pedunculated or semipedunculated SICC.

Laterally spreading type of colorectal adenoma exhibits a unique methylation phenotype and K-ras mutations

BACKGROUND & AIMS

Laterally spreading tumors (LST), characterized by superficial extension along the colonic lumen, have recently been detected by colonoscopy. However, genetic and epigenetic characteristics of these tumors were scarcely reported.

METHODS

A total of 205 sporadic colorectal adenoma tissues (157 protruded-type, 23 granular-type LST (G-LST), 12 flat-type LST (F-LST), and 13 flat-type smaller than 1 cm) were collected. CpG island methylator phenotype (CIMP) was determined by examination of methylation status at p16, methylated in tumor (MINT) 1, 2, 12, and 31 loci. K-ras codon 12 and 13 point mutations were also examined. The relationship between macroscopic appearance and CIMP status or K-ras mutations was analyzed.

RESULTS

Among adenomas larger than 1 cm, CpG island methylation involving 2 or more loci (CIMP-high) was more likely to be observed in G-LST (14/23, 61%) than in protruded-type adenomas (18/73, 25%) (P = .002). The prevalence of K-ras mutations in G-LST (18/23, 78%) was significantly higher than that in protruded-type adenomas (18/73, 25%) (P < .0001). Moreover, the prevalence of CIMP-high and K-ras mutations in G-LST located in the proximal colon was much higher (11/13, 85%; and 12/13, 92%, respectively). In contrast, F-LST exhibited low prevalence of CIMP-high (1/12, 8%) and K-ras mutations (2/12, 16%).

CONCLUSIONS

High prevalence of CIMP-high and K-ras mutations in G-LST, especially in the proximal colon, could strongly suggest that G-LST appearance is associated with a unique carcinogenic pathway.

Actual number of tumor budding as a new tool for the individualization of treatment of T1 colorectal carcinomas

BACKGROUND AND AIM

Treatment of T1 colorectal carcinomas, either local excision including endoscopic polypectomy or radical surgery, has always been problematic in everyday practice. Although previous studies have revealed that tumor budding at the invasive margin can be a marker for the malignant potential of T1 colorectal carcinomas, the evaluation of tumor budding has not been standardized as yet. In the present study, we attempted to apply the actual number of tumor budding units for the individualization of treatment in T1 colorectal carcinomas.

METHODS

In 76 T1 colorectal carcinomas, associations between lymph node metastasis and clinicopathological parameters were examined statistically. A mathematical formula for predicting the risk of lymph node metastasis was constructed and decision analysis was attempted to determine individually the indication for additional surgery after endoscopic mucosal resection of T1 colorectal carcinomas.

RESULTS

Of the clinicopathological parameters examined, multivariate analysis showed that the actual number of tumor budding units alone was significantly associated with lymph node metastasis. The probability of lymph node metastasis was calculated as Z = 0.07 x (budding counts) - 3.726, probability = 1/1 + e(-Z). The more the budding counts, the higher the probability of lymph node metastasis. This formula was able to accurately predict lymph node metastasis in successive cases. The actual number of tumor budding units can be applied to decision analysis in determining an indication for additional surgery after endoscopic mucosal resection of T1 colorectal carcinomas.

CONCLUSIONS

The actual number of tumor budding units may be useful in the decision making for patient-oriented treatment of T1 colorectal carcinomas.

Flat colorectal neoplasms and the impact of the revised Vienna Classification on their reporting: a case-control study in UK and Japanese patients

OBJECTIVE

The prevalence and interpretation of flat colorectal neoplasms in the East or West remain highly variable. Several factors may contribute to this variability including differences in reporting techniques between Japanese and Western histopathologists when lesions are classified. The aims of this study were (i) to determine the frequency and characteristics of flat colorectal neoplasms in British and Japanese patients, (ii) to examine whether histopathological discrepancies exist between Western and Japanese-trained pathologists applying conventional classification methods and (iii) to determine the impact of the revised Vienna Classification on any differences observed.

MATERIAL AND METHODS

One hundred and forty-four patients in the United Kingdom with neoplastic lesions prospectively identified by a colonoscopist, fully-trained in Japan, were age and gender-matched with 144 Japanese patients with neoplastic lesions detected by the same colonoscopist. Two British and two Japanese pathologists were independently asked to assess all neoplasms using both conventional and revised Vienna Classification methods.

RESULTS

No significant difference in the frequency of flat neoplasms was found between British and Japanese patients; however, flat neoplasia from Japanese patients tended to contain more advanced pathologies. Discrepancies in histological diagnoses were observed between pathologists but which were reduced with the revised Vienna Classification. Japanese pathologists tended to diagnose higher grades of dysplasia for the same lesion compared to their British counterparts.

CONCLUSIONS

The frequency of flat neoplasms in British and Japanese patients is similar. However, Japanese lesions, especially flat (IIb) and slightly depressed (IIc) neoplasms tend to be more biologically aggressive. The revised Vienna Classification achieves greater consensus.

Depressed-type (0-IIc) colorectal neoplasm in patients with family history of first-degree relatives with colorectal cancer: A cross-sectional study

AIM: To investigate the correlation of depressed-type (0-IIc) colorectal neoplasm and family history of first-degree relatives (FDR) with colorectal cancer (CRC).

METHODS: This cross-sectional study was conducted from June 2000 to October 2002 at National Cancer Center Hospital East. Eligible patients undergoing initial total colonoscopy were surveyed regarding family history of CRC among FDR by a questionnaire prior to colonoscopic examinations. All endoscopic findings during colonoscopy were recorded and the macroscopic classification of the early stage neoplasm/cancer was classified into two types (0-IIc vs non 0-IIc). Odds ratios (OR) and 95% confidence intervals (CI) were calculated by univariate and multivariate logistic regression to estimate the association between macroscopic features and clinicopathological data including gender, age, and family history of FDR with CRC.

RESULTS: The OR of an association between family history of FDR with CRC and overall early stage neoplasm adjusted by gender and age was 1.85 (95% CI: 1.31-2.61, P = 0.0004), that for non 0-IIc neoplasm was 1.71 (95% CI: 1.22-2.41, P = 0.0017) and for 0-IIc colorectal neoplasm was 2.78 (95% CI: 1.49-5.16, P = 0.0031).

CONCLUSION: Our study shows a significant association between a family history of FDR with CRC and 0-IIc colorectal neoplasm. When patients with a family history of FDR with CRC undergo colonoscopy, colonoscopists should check carefully for not only polypoid, but also depressed-type (0-IIc) lesions.

The adenoma carcinoma sequence: an indoctrinated model for tumorigenesis, but is it always a clinical reality?

OBJECTIVE

Evidence exists to support alternative pathways to the adenoma carcinoma sequence. Some mutations in key onco-suppressor genes relate to the anatomical site of the tumour. This link is typified by microsatellite instability and proximal neoplasia. However, rectal tumours are rarely considered separately. We hypothesized that tumour behaviour in the rectum may differ in terms of pathogenesis and malignant propensity. Therefore, we aimed to look for an association between the histopathological features of adenomas and their anatomical location as compared with the distribution of cancers.

METHODS

A single centre prospective study was undertaken over a four-year period. Patients referred to a colorectal assessment clinic with bowel symptoms underwent a minimum investigation of flexible sigmiodoscopy. Neoplastic lesions were either biopsied or removed after noting distance from the anal margin. Adenomas, differentiated by size, villous architecture and degree of dysplasia were compared to both early and advanced carcinomas.

RESULTS

Of 4089 patients, polyps were identified in 8.0% and cancer in 4.2%. There was a clear difference between the distribution of cancer and adenomas > 1 cm, P < 0.001. All degrees of dysplasia in large adenomas were more prevalent in the sigmoid colon as compared to cancer, P < 0.001. Seventy-five percent of high risk diminutive adenomas were rectal in origin.

CONCLUSION

Our data provides indirect evidence to support the concept that a significant proportion of rectal cancers may arise via an alternative pathway to the Vogelstein model. Polyp behaviour along with malignant propensity may actually be site dependent, with rectal polyps harbouring a more aggressive phenotype.

Endoscopic Mucosal Resection of Lateral Spreading Tumors of the Colon Using a Novel Solution

Lateral spreading tumors (LSTs) of the colon are lesions over 10 mm in diameter that are low in height and grow superficially. They are increasingly being diagnosed in Western cohorts. The aim of this study was to investigate the safety and efficacy of dextrose 50% solution in the endoscopic mucosal resection (EMR) of LSTs. The study population consisted of 21 patients with LSTs of the colorectum. The mean size of the LSTs was 23.52+/-13.60 mm. Dextrose 50% solution was injected, via a variceal needle, into the submucosa to lift up the LST sufficiently from the proper muscle layer. Subsequently, a snare was positioned around the lesion and then closed while being pressed against the mucosa, with suction being applied to draw the lesion into the snare. Blended current was used for resection. If necessary, a piecemeal technique was used to achieve complete resection. Immediate and delayed complications were recorded. After the EMR, patients were followed up at 3, 6, and 12 months or later, using total colonoscopy. Endoscopic resection was completed in all LSTs. Of the 21 LSTs, 15 (71.4%) were resected en bloc and 6 (28.6%) piecemeal. The mean amount of injected dextrose 50% solution was 14.86+/-9.13 mL. One patient (4.78%) had immediate bleeding after EMR, which was stopped endoscopically. Histologic examination of resected LSTs showed adenoma with high-grade dysplasia 9 (42.9%), adenoma with low-grade dysplasia 10 (47.6%), and invasive carcinoma 2 (9.5%). Twenty patients were followed up for 37.9+/-24.03 months. Local recurrent disease was detected in 4 patients (20%), all within 6 months of the index EMR. These recurrent lesions were completely resected endoscopically. The contribution of submucosal injection of dextrose 50% is significant for a safe and efficient EMR of LSTs of the colorectum.

BRAF mutations and phosphorylation status of mitogen-activated protein kinases in the development of flat and depressed-type colorectal neoplasias

Although some molecular differences between flat-depressed neoplasias (FDNs) and protruding neoplasias (PNs) have been reported, it is uncertain if the BRAF mutations or the status of phosphorylated mitogen-activated protein kinase (p-MAPK) are different between theses two groups. We evaluated the incidence of BRAF and KRAS mutations, high-frequency microsatellite instability (MSI-H), and the immunohistochemical status of p-MAPK in the nonserrated neoplasias (46 FDNs and 57 PNs). BRAF mutations were detected in four FDNs (9%) and none of PNs (P=0.0369 by Fisher's exact test). KRAS mutations were observed in none of FDNs and in 14 PNs (25%; P=0.0002 by Fisher's exact test). MSI-H was detected in seven out of 44 FDNs (16%) and in one out of 52 of PNs (2%) (P=0.022 by Fisher's exact test). Type B and C immunostaining for p-MAPK was observed in 34 out of 46 FDNs (72%), compared with 24 out of 55 PNs (44%; P=0.0022 by χ² test). There was no significant difference in the type B and C immunostaining of p-MAPK between FDNs with and without BRAF mutations. BRAF and KRAS mutations are mutually exclusive in the morphological characteristics of colorectal nonserrated neoplasia. Abnormal accumulation of p-MAPK protein is more likely to be implicated in the tumorigenesis of FDNs than of PNs. However, this abnormality in FDNs might occur via the genetic alteration other than BRAF or KRAS mutation.

Symptomatic presentation of early colorectal cancer

INTRODUCTION

It is believed that increased detection of earlier stage colorectal cancer can only be achieved by screening asymptomatic individuals. We describe a referral pathway for a symptomatic population which achieves a 30% Dukes' A detection rate.

PATIENTS AND METHODS

From October 1999, 4253 patients with distal colonic symptoms, referred by general practitioners, completed a patient consultation questionnaire (PCQ) linked to a computerised record. A weighted numerical score (WNS) was derived for each patient. Patients underwent flexible sigmoidoscopy, a diagnostic outcome was recorded and later Dukes' stage appended. Early and advanced colorectal cancers were separated and PCQ derived symptom profiles compared. Chi-square, Fisher exact, Student's t-test and logistic regression were used for statistical analysis.

RESULTS

A total of 183 patients had cancer, 55 (30%) were Dukes' A early colorectal cancers, 112 were advanced colorectal cancers (Dukes' B-D) and 16 could not be staged. Early colorectal cancers had significant symptoms and comparable profile to advanced colorectal cancers. The tendency in advanced colorectal cancers was towards greater symptom prevalence for only a few primary and systemic symptoms, as reflected by a higher WNS of 75 (P = 0.001).

CONCLUSIONS

Early colorectal cancers do have significant symptoms which can easily be captured by a PCQ and objective scoring tool in the secondary care setting. Detection of these cancers has the potential to improve survival.

Increased density and diameter of lymphatic microvessels correlate with lymph node metastasis in early stage invasive colorectal carcinoma

To determine whether lymphangiogenesis was associated with the development of colorectal carcinoma and whether the mean maximal diameter of lymphatic microvessels (LMMMD) or lymphatic microvessel density (LMVD) is associated with lymph node metastasis in early stage invasive colorectal carcinoma (T1 carcinoma), we used immunohistochemical staining with podoplanin to measure LMMMD and LMVD in intratumoral (LMMMDit, LMVDit) and peritumoral areas (LMMMDpt, LMVDpt) of T1 carcinomas (n=87). By comparing the LMMMD and LMVD in normal large intestine (n=10), adenoma (n=15), and Tis carcinoma (n=15), we found out that the LMVDpt in T1 carcinoma with lymphatic vessel invasion (LVI) was significantly high (P<0.001), and there was a significant decrease in LMMMDpt in T1 carcinoma (P=0.031). Both LMMMDpt and LMVDpt were significantly increased in the T1 carcinomas, with LVI compared with the T1 carcinomas without LVI (P=0.018, P=0.003). Multivariate analysis revealed that LVI and combined greater LMMMDpt and greater LMVDpt were associated with lymph node metastases (P=0.005, P=0.036). These results indicate that lymphangiogenesis might be induced in the surrounding tumor areas of the T1 colorectal carcinoma with LVI; thus, evaluation of the diameter and density of lymphatic microvessels is important in T1 colorectal carcinoma to predict lymph node metastases.

Early colorectal cancer: concept, diagnosis, and management

In colorectal cancers, although flat and depressed-type lesions are found by regular endoscopic view, magnification and pit-pattern observation are vital parts of the precise diagnosis of the lesion. The depressed-type lesions appear to have a prominent tendency to show malignant characteristics, and the recognition and timely treatment of such lesions is important for improving the morbidity and mortality of colorectal cancer. Chromoscopy is mandatory for an accurate diagnosis of these lesions. The pit-pattern classification correlates well with actual histological findings and can provide important additional information prior to endoscopic treatment of the lesion.

Flat and depressed neoplasms of the colon in Western populations

Flat and depressed neoplasms of the colon are defined endoscopically as visible non-exophytic, flat and/or depressed mucosal lesions with a height less than half the diameter of the lesion. These neoplasms are typically smaller than their polypoid counterparts, and might be associated with a more aggressive biological behavior. While these lesions have been described in cohorts of Japanese patients for over two decades, their existence in Western populations has been less well described. This review focuses on the epidemiology and biological behavior of flat and depressed neoplasms in Western populations as well as the strategies for their identification, endoscopic staging, and therapy.

The role of high-magnification-chromoscopic colonoscopy in hereditary nonpolyposis colorectal cancer screening: a prospective "back-to-back" endoscopic study

BACKGROUND

In hereditary nonpolyposis colorectal cancer flat and diminutive adenomas occur, particularly in the right colon. Such lesions may assume a high risk of malignant transformation. Interval cancers are known to occur in this group. Chromoscopic colonoscopy enhances detection in patients assuming a moderate to high lifetime risk of colorectal cancer.

AIM

To prospectively assess the efficacy of high-magnification-chromoscopic colonoscopy for the detection of neoplastic lesions in patients undergoing hereditary nonpolyposis colorectal cancer screening.

METHODS

Twenty-five asymptomatic patients fulfilling modified Amsterdam criteria underwent "back-to-back" colonoscopy. Conventional colonoscopy with targeted chromoscopy was performed initially followed by pan-colonic chromoscopic colonoscopy. Diagnostic extubation times and volumes of normal saline and indigo carmine (IC) were controlled.

RESULTS

Using conventional colonoscopy and targeted chromoscopy 24 lesions were detected in 13 patients (20 exophytic/4 flat). Pan-colonic chromoscopy identified a further 52 lesions in 16 patients (17 exophytic/35 flat). Pan-chromoscopy identified significantly more adenomas than conventional colonoscopy (p= 0.001) and a significantly high number of flat adenomas (p= 0.004).

CONCLUSIONS

Pan-colonic chromoscopic colonoscopy improves detection of significant neoplastic lesions in hereditary nonpolyposis colorectal cancer screening. Pan-chromoscopy may help better stratify colorectal cancer "risk" in this cohort and aid planning of surveillance colonoscopic follow-up.

Practical uses of chromoendoscopy and magnification at colonoscopy

New technologies in the form of high-magnification or zoom colonoscopy complemented by chromoscopic agents permits early detection of neoplastic colorectal lesions, particularly flat and depressed types. Establishing suitability for endoscopic resection or surgical excision can be enhanced using these techniques. Chromoscopic colonoscopy may play an important role in the routine endoscopic colorectal cancer surveillance programs in patients assuming a high risk of colorectal neoplasia. This article summarizes recent data regarding the prevalence and histopathologic characteristics of flat and depressed colorectal lesion in Western cohorts and describes how their detection and management can be improved by chromoscopy and magnification technology. The techniques required for chromoscopic colonoscopy and magnification imaging are outlined along with a review of the literature on these subjects.

Endoscopic mucosal resection for colonic non-polypoid neoplasms

BACKGROUND

Colonic neoplastic lesions can be classified morphologically into polypoid and non-polypoid types. Non-polypoid lesions have a higher malignant potential than polypoid lesions. Removing these lesions and obtaining integral specimen for histopathology evaluation during colonoscopy examination is an important task. Endoscopic mucosal resection (EMR) is an alternative to surgery for removing of non-polypoid lesions of the GI tract. This study assessed the safety, efficacy, and clinical outcomes of EMR.

PATIENTS AND METHODS

From October 2000 to October 2003 during the routine colonoscopy performed at one medical center, identified 152 non-polypoid colonic neoplasms in 149 patients (92 males, 57 females) were found. The mean patient age was 57.8 +/- 15.5 yr (range 32-80 yr). EMR was performed for lesions suspected of being neoplastic tumors via magnification colonoscopy with the indigo carmine dye spray method. The lesions were removed via EMR with pure cutting current after which hemoclips were applied to the resected wounds.

RESULTS

The study identified 40 flat type lesions, 106 lateral spreading tumors, and 6 depressed lesions that were completely resected. The mean size of lesions was 19.4 +/- 10.3 mm (range 6-60 mm). Histological findings were 4 adenocarcinomas, 59 with high-grade adenoma/dysplasia, and 89 with low-grade adenoma/dysplasia. Two patients experienced bleeding immediately following EMR, while adequate hemostasis was achieved using hemoclips. Neither delayed bleeding nor perforation developed following EMR.

CONCLUSION

EMR by using pure cutting current and hemoclip is a useful method for obtaining integral specimen for accurate pathologic assessment. This method provides a safe and minimally invasive technique managing of colonic non-polypoid lesions.

Analysis of K-ras mutations and expression of cyclooxygenase-2 and gastrin protein in laterally spreading tumors

BACKGROUND AND AIM

Recent advances in colonoscopic techniques have led to the increased detection of, and interest in, superficial type colorectal tumors, and a new category, the 'laterally spreading tumor (LST)', has been proposed. However, the characteristics of the genetic alterations in these LSTs have not yet been fully determined. We therefore classified LSTs as LST-granular (LST-G) or LST-non-granular (LST-NG), according to their macroscopic appearance, and examined the genetic alterations in these two tumor groups compared with those in protruded type tumors.

METHODS

We obtained a total of 62 colorectal tumors, including 26 protruded type, 17 LST-G and 19 LST-NG, from specimens resected surgically or endoscopically. We examined K-ras codon 12 mutations by using the polymerase chain reaction-restriction fragment length polymorphism method and by fluorescence direct sequencing. We also performed immunohistochemistry to analyze cyclooxygenase (COX)-2 and gastrin abnormalities.

RESULTS

The incidence of K-ras mutation was 50.0% in protruded type tumors, 76.5% in LST-G, and 26.3% in LST-NG. The frequencies of COX-2 overexpression were 73.1, 88.2, and 31.6%, respectively, and those of gastrin overexpression were 61.5, 82.4, and 26.3%, respectively. Therefore, LST-G is similar to protruded type tumors in that the incidence of K-ras mutation and the frequencies of COX-2 and gastrin overexpression are high. LST-NG differs from both of these tumor types in that the values of these three indicators are all low.

CONCLUSIONS

These results show that LST-G and LST-NG have different genetic alterations.

A new sinker-assisted endoscopic submucosal dissection for colorectal cancer

BACKGROUND

Endoscopic submucosal dissection (ESD) is accepted as a minimally invasive treatment for early gastric cancer, but it is not widely used to treat the colorectum because of its degree of technical difficulty. Thus, a noninvasive tool that facilitates the direct visualization of the submucosal layer is needed.

METHODS

Traction-assisted dissection was performed on 4 superficial lesions. The system consisted of a metallic clip attached by a nylon line to a sinker 6 x 4 x 4 mm in size and weighing 1 g. After partially dissecting the submucosa, the clip was attached to the edge of the exfoliated mucosa and the weight of the sinker pulled down the partly resected lesion.

OBSERVATIONS

In all 4 cases, the sinker allowed direct visualization of the cutting line, and en bloc resection was successfully accomplished.

CONCLUSIONS

These preliminary results suggest that sinker-assisted ESD is effective for the complete removal of selected superficial early colorectal cancer.